Euthanasia is probably the single biggest difference between medical care for humans and veterinary care for pets.

When an animal starts to suffer from the discomfort, pain and indignity of terminal illness or advanced old age, it's normal in our culture for vets to release them from their suffering through the kind act of euthanasia ( a word which is derived from the Greek for 'good death')

It's far more complicated for humans: we have such a deep aversion to the taking of human life that even when it might seem like an act of kindness, it's against the law in most countries to carry out euthanasia.

As a vet, I have to euthanase a much-loved pet on almost every working day: it's one of the most challenging parts of my job. Owners are often devastated, and emotions can run high in the consulting room. The witnessing of such intense grief is never easy. The only silver lining is the fact that euthanasia is carried out as an act of mercy, relieving an animal of pain and distress. So when it is done, it's done to help an animal.

Before carrying out euthanasia, it's normal for a vet to describe exactly what's going to happen. The animal is gently restrained, usually by a veterinary nurse. The vet then gives an injection of a lethal dose of medication, which has the effect of causing the animal to first, fall deeply asleep, and once the animal is unconscious, the drug causes the heart to stop.

This all happens far more quickly than most people expect. Literally, as the injection is given, the animal's body relaxes as the drug affects their central nervous system.

Most people stay with their pets while this happens. It is a peaceful act to observe in most cases, but for an owner who is deeply attached to a pet, it can be very distressing. Saying goodbye, forever, is never easy.

For this reason, some owners choose not to stay with their pets. For them, the thought of being with their pet while this happens is just too distressing. They prefer to say their goodbyes to the living animal, then to walk away, out of the door, carrying their private grief with them. Then once they have gone, the same act takes place: the vet nurse holds the dog while the injection is given.

I don't know the exact figures, but I suspect that around one in ten or one in twenty people choose not to be with their pets at the end.

Vets make it very clear to owners that it is up to them whether they stay or go: it is a very personal decision. Animals live in the moment, and have no awareness of precisely what is happening. They are there, in the room, in the arms of the vet nurse, then gradually, they start to feel woozy, then they're asleep. They don't contemplate their upcoming death because they don't know it's happening. They don't actively miss their owners, because they don't have time: the vet nurse is hugging them, and they are nearly always calm and comfortable.

Unfortunately, a misleading post on this topic went viral recently. The post was published via a vet clinic in South Africa. The message was as follows:

'I beg you DO NOT LEAVE THEM. Do not make them transition from life to death in a room full of strangers in a place they don't like. The thing you people need to know that most of you don't is that THEY SEARCH FOR YOU WHEN YOU LEAVE THEM BEHIND!!!! They search every face in the room for their loved person. They don't understand why you left them when they are sick, scared, old, or dying from cancer and they need your comfort.'

The post signed off with, 'From a tired broken-hearted vet', and it was spread via social media, being shared millions of times.

However, in every veterinary forum where this has been discussed (and it has been widely debated by vets in the past few weeks), nearly every vet has stated that they NEVER recall a pet being upset when left behind by their owners for euthanasia. In nearly every case, the animals passively sit there while the fur is clipped off their leg and the lethal injection is given. The veterinary staff are calm, reassuring and caring, and the animals react well to this.

Animals are like humans in many ways, but they do not have the same size of forebrain as us. This means that they do not know that death is coming when left in for euthanasia, and they do not feel that they have been 'abandoned'. Animals are left alone for short periods for many reasons, from vet visits to grooming to day care, and most pets are quite content to be on their own, without their owners, for short periods.

Many vets are angry about the viral post because they know that it will make some owners upset, guilty and remorseful if they did not stay with their pet at the end. If the post was true, then perhaps this would be acceptable, but because it is absolutely untrue, many people will be caused distress for no reason.

There is nothing at all wrong with leaving your pet before the act of euthanasia is carried out. It is a human choice: do you wish to stay, or do you wish to go? Animals do not suffer more if you decide to go.

If you've done this in the past, please do not worry. And if you feel like doing this in the future, please do so.

One tired, emotional vet's social media post should not be taken as 'the truth'.